Problem solved!
Thank you for your help. I have managed to track down the following which was successful for me and I post here in case anyone else has the same problem.
The sound quality is poor/garbled/ crackles/skips.
This most often indicates the need to adjust your QuickTime settings. iTunes uses QuickTime for audio playback. Many folks have provided this solution, but MacMuse seems to have the easiest version to read.
* quit iTunes
* open Windows Control Panel - QuickTime entry
* Sound Out option, set it to 'wavout:Windows preferred device' -or- 'wavout:name_of_soundcard'
* reboot
* try iTunes again
If that doesn't help, audio drivers are the next tactic. Check for the card's vendor details in Device Manager and then hit their website (not Microsoft) for any upgrades.